4-1
Semiconductor
March 1997
82C54
CMOS Programmable Interval Timer
Features
• 8MHz to 12MHz Clock Input Frequency
• Compatible with NMOS 8254
- Enhanced Version of NMOS 8253
• Three Independent 16-Bit Counters
• Six Programmable Counter Modes
• Status Read Back Command
• Binary or BCD Counting
• Fully TTL Compatible
• Single 5V Power Supply
• Low Power
- ICCSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10µA
- ICCOP . . . . . . . . . . . . . . . . . . . . . . . . . .10mA at 8MHz
• Operating Temperature Ranges
- C82C54 . . . . . . . . . . . . . . . . . . . . . . . . . .0oC to +70oC
- I82C54 . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to +85oC
- M82C54 . . . . . . . . . . . . . . . . . . . . . . . -55oC to +125oC
Description
The Harris 82C54 is a high performance CMOS Programma-
ble Interval Timer manufactured using an advanced 2 micron
CMOS process.
The 82C54 has three independently programmable and
functional 16-bit counters, each capable of handling clock
input frequencies of up to 8MHz (82C54) or 10MHz
(82C54-10) or 12MHz (82C54-12).
The high speed and industry standard configuration of the
82C54 make it compatible with the Harris 80C86, 80C88,
and 80C286 CMOS microprocessors along with many other
industry standard processors. Six programmable timer
modes allow the 82C54 to be used as an event counter,
elapsed time indicator, programmable one-shot, and many
other applications. Static CMOS circuit design insures low
power operation.
The Harris advanced CMOS process results in a significant
reduction in power with performance equal to or greater than
existing equivalent products.
Pinouts
82C54 (PDIP, CERDIP, SOIC)
TOP VIEW 82C54 (PLCC/CLCC)
TOP VIEW
1
2
3
4
5
6
7
8
9
10
11
12
16
17
18
19
20
21
22
23
24
15
14
13
D7
D6
D5
D4
D3
D2
D1
D0
CLK 0
OUT 0
GATE 0
GND
VCC
RD
CS
A1
A0
OUT 2
CLK 1
GATE 1
OUT 1
WR
CLK 2
GATE 2
GND
NC
OUT 1
GATE 1
CLK 1
OUT 0
GATE 0
D7
NC
VCC
WR
RD
D5
D6
CS
A1
A0
CLK2
NC
GATE 2
OUT 2
1234
5
6
7
8
9
10
11
12 13 14 15 16 17 18
19
20
21
22
23
24
25
262728
D3
D2
D1
D0
D4
NC
CLK 0
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.
Copyright © Harris Corporation 1997 File Number 2970.1
4-2
Functional Diagram
Ordering Information
PART NUMBERS TEMPERATURE
RANGE PACKAGE PKG. NO.8MHz 10MHz 12MHz
CP82C54 CP82C54-10 CP82C54-12 0oC to +70oC 24 Lead PDIP E24.6
IP82C54 IP82C54-10 IP82C54-12 -40oC to +85oC 24 Lead PDIP E24.6
CS82C54 CS82C54-10 CS82C54-12 0oC to +70oC 28 Lead PLCC N28.45
IS82C54 IS82C54-10 IS82C54-12 -40oC to +85oC 28 Lead PLCC N28.45
CD82C54 CD82C54-10 CD82C54-12 0oC to +70oC 24 Lead CERDIP F24.6
ID82C54 ID82C54-10 ID82C54-12 -40oC to +85oC 24 Lead CERDIP F24.6
MD82C54/B MD82C54-10/B MD82C54-12/B -55oC to +125oC 24 Lead CERDIP F24.6
MR82C54/B MR82C54-10/B MR82C54-12/B -55oC to +125oC 28 Lead CLCC J28.A
SMD # 8406501JA - 8406502JA -55oC to +125oC 24 Lead CERDIP F24.6
SMD# 84065013A - 84065023A -55oC to +125oC 28 Lead CLCC J28.A
CM82C54 CM82C54-10 CM82C54-12 0oC to +70oC 24 Lead SOIC M24.3
Pin Description
SYMBOL DIP PIN
NUMBER TYPE DEFINITION
D7 - D0 1 - 8 I/O DATA: Bi-directional three-state data bus lines, connected to system data bus.
CLK 0 9 I CLOCK 0: Clock input of Counter 0.
OUT 0 10 O OUT 0: Output of Counter 0.
GATE 0 11 I GATE 0: Gate input of Counter 0.
GND 12 GROUND: Power supply connection.
OUT 1 13 O OUT 1: Output of Counter 1.
GATE 1 14 I GATE 1: Gate input of Counter 1.
CLK 1 15 I CLOCK 1: Clock input of Counter 1.
GATE 2 16 I GATE 2: Gate input of Counter 2.
OUT 2 17 O OUT 2: Output of Counter 2.
CONTROL
WORD
REGISTER
READ/
WRITE
LOGIC
DATA/
BUS
BUFFER
COUNTER
2
COUNTER
1
COUNTER
0
INTERNAL BUS
INTERNAL BUS
CONTROL
LOGIC
CONTROL
WORD
REGISTER
STATUS
LATCH
STATUS
REGISTER
CLK n
GATE n
OUT n
OUT 2
GATE 2
CLK 2
OUT 1
GATE 1
CLK 1
OUT 0
GATE 0
CLK 0
WR
RD
D7 - D0
A0
A1
CS
OLMOLL
CE
CRMCRL
COUNTER INTERNAL BLOCK DIAGRAM
8
82C54
4-3
Functional Description
General
The 82C54 is a programmable interval timer/counter
designed f or use with microcomputer systems . It is a gener al
purpose, multi-timing element that can be treated as an
array of I/O ports in the system software.
The 82C54 solves one of the most common problems in any
microcomputer system, the generation of accurate time
delays under software control. Instead of setting up timing
loops in software, the programmer configures the 82C54 to
match his requirements and programs one of the counters
for the desired delay. After the desired delay, the 82C54 will
interrupt the CPU. Software overhead is minimal and vari-
able length delays can easily be accommodated.
Some of the other computer/timer functions common to micro-
computers which can be implemented with the 82C54 are:
• Real time clock
• Event counter
• Digital one-shot
• Programmable rate generator
• Square wave generator
• Binary rate multiplier
• Complex waveform generator
• Complex motor controller
Data Bus Buffer
This three-state, bi-directional, 8-bit buffer is used to inter-
face the 82C54 to the system bus (see Figure 1).
Read/Write Logic
The Read/Write Logic accepts inputs from the system bus and
generates control signals for the other functional blocks of the
82C54. A1 and A0 select one of the three counters or the Con-
trol Word Register to be read from/written into. A “low” on the
RD input tells the 82C54 that the CPU is reading one of the
counters. A “lo w” on the WR input tells the 82C54 that the CPU
is writing either a Control Word or an initial count. Both RD an d
WR are qualified by CS; RD and WR are ignored unless the
82C54 has been selected by holding CS l o w.
CLK 2 18 I CLOCK 2: Clock input of Counter 2.
A0, A1 19 - 20 I ADDRESS: Select inputs for one of the three counters or Control Word Register for read/write
operations. Normally connected to the system address bus.
CS 21 I CHIP SELECT: A low on this input enables the 82C54 to respond to RD and WR signals. RD and
WR are ignored otherwise.
RD 22 I READ: This input is low during CPU read operations.
WR 23 I WRITE: This input is low during CPU write operations.
VCC 24 VCC: The +5V power supply pin. A 0.1µF capacitor between pins VCC and GND is recommended
for decoupling.
Pin Description
(Continued)
SYMBOL DIP PIN
NUMBER TYPE DEFINITION
A1 A0 SELECTS
0 0 Counter 0
0 1 Counter 1
1 0 Counter 2
1 1 Control Word Register
CONTROL
WORD
REGISTER COUNTER
2
COUNTER
1
COUNTER
0
INTERNAL BUS
OUT 2
GATE 2
CLK 2
OUT 1
GATE 1
CLK 1
OUT 0
GATE 0
CLK 0
WR
RD
D7 - D0
A0
A1
CS
FIGURE 1. DATA BUS BUFFER AND READ/WRITE LOGIC
FUNCTIONS
8DATA/
BUS
BUFFER
READ/
WRITE
LOGIC
82C54
4-4
Control Word Register
The Control Word Register (Figure 2) is selected by the
Read/Write Logic when A1, A0 = 11. If the CPU then does a
write operation to the 82C54, the data is stored in the Con-
trol W ord Register and is interpreted as a Control Word used
to define the Counter operation.
The Control Word Register can only be written to; status
information is available with the Read-Back Command.
Counter 0, Counter 1, Counter 2
These three functional blocks are identical in operation, so
only a single Counter will be described. The internal block
diagram of a signal counter is shown in Figure 3. The
counters are fully independent. Each Counter may operate
in a different Mode.
The Control Word Register is shown in the figure; it is not
par t of the Counter itself, but its contents determine how the
Counter operates.
The status register, shown in the figure, when latched, con-
tains the current contents of the Control Word Register and
status of the output and null count flag. (See detailed expla-
nation of the Read-Back command.)
The actual counter is labeled CE (f or Counting Element). It is
a 16-bit presettable synchronous down counter.
OLM and OLL are two 8-bit latches. OL stands for “Output
Latch”; the subscripts M and L for “Most significant byte” and
“Least significant byte”, respectively. Both are normally referred
to as one unit and called just OL. These latches nor mally “fol-
low” the CE, b ut if a suitable Counter Latch Command is sent to
the 82C54, the latches “latch” the present count until read by
the CPU and then return to “following” the CE. One latch at a
time is enabled b y the counter’s Control Logic to drive the inter-
nal bus. This is how the 16-bit Counter communicates over the
8-bit internal bus. Note that the CE itself cannot be read; when-
e v er y ou read the count, it is the OL that is being read.
Similarly, there are two 8-bit registers called CRM and CRL (for
“Count Register”). Both are normally referred to as one unit and
called just CR. When a new count is written to the Counter, the
count is stored in the CR and later transferred to the CE. The
Control Logic allows one register at a time to be loaded from
the internal bus. Both bytes are transferred to the CE simulta-
neously. CRM and CRL are cleared when the Counter is pro-
grammed for one byte counts (either most significant byte only
or least significant byte only) the other byte will be zero. Note
that the CE cannot be written into; whenever a count is written,
it is written into the CR.
The Control Logic is also shown in the diagram. CLK n,
GATE n, and OUT n are all connected to the outside world
through the Control Logic.
82C54 System Interface
The 82C54 is treated by the system software as an array of
peripheral I/O ports; three are counters and the fourth is a
control register for MODE programming.
Basically, the select inputs A0, A1 connect to the A0, A1
address bus signals of the CPU. The CS can be derived
directly from the address bus using a linear select method or
it can be connected to the output of a decoder.
READ/
WRITE
LOGIC
DATA/
BUS
BUFFER
INTERNAL BUS
OUT 2
GATE 2
CLK 2
OUT 1
GATE 1
CLK 1
OUT 0
GATE 0
CLK 0
WR
RD
D7 - D0
A0
A1
CS
FIGURE 2. CONTROL WORD REGISTER AND COUNTER
FUNCTIONS
8
CONTROL
WORD
REGISTER COUNTER
2
COUNTER
1
COUNTER
0
INTERNAL BUS
CONTROL
LOGIC
CONTROL
WORD
REGISTER
STATUS
LATCH
STATUS
REGISTER
CLK n
GATE n
OUT n
OLMOLL
CE
CRMCRL
FIGURE 3. COUNTER INTERNAL BLOCK DIAGRAM
82C54
4-5
Operational Description
General
After power-up, the state of the 82C54 is undefined. The
Mode, count v alue , and output of all Counters are undefined.
How each Counter operates is determined when it is pro-
grammed. Each Counter must be programmed before it can
be used. Unused counters need not be programmed.
Programming the 82C54
Counters are programmed by writing a Control Word and
then an initial count.
All Control Words are written into the Control Word Register,
which is selected when A1, A0 = 11. The Control W ord spec-
ifies which Counter is being programmed.
By contrast, initial counts are written into the Counters, not
the Control Word Register. The A1, A0 inputs are used to
select the Counter to be written into. The for mat of the initial
count is determined by the Control Word used.
FIGURE 4. 82C54 SYSTEM INTERFACE
Write Operations
The programming procedure for the 82C54 is very flexible.
Only two conventions need to be remembered:
1.For Each Counter, the Control Word must be written
before the initial count is written.
2.The initial count must follow the count format specified in the
Control W ord (least significant byte only, most significant b yte
only, or least significant byte and then most significant b yte).
Since the Control Word Register and the three Counters have
separate addresses (selected by the A1, A0 inputs), and each
Control W ord specifies the Counter it applies to (SC0, SC1 bits),
no special instruction sequence is required. Any programming
sequence that f ollo ws the con v entions abo v e is acceptab le .
Control Word Format
A1, A0 = 11; CS = 0; RD = 1; WR = 0
D7 D6 D5 D4 D3 D2 D1 D0
SC1 SC0 RW1 RW0 M2 M1 M0 BCD
ADDRESS BUS (16)
CONTROL BUS
DATA BUS (8)
I/OR I/OW
WR
RD
CS
A0
A1
A1 A0
8
COUNTER
0
OUTGATECLK
COUNTER
1COUNTER
2
OUTGATECLK OUTGATECLK
D0 - D7
82C54
SC - Select Counter
SC1 SC0
0 0 Select Counter 0
0 1 Select Counter 1
1 0 Select Counter 2
1 1 Read-Back Command (See Read Operations)
RW - Read/Write
RW1 RW0
0 0 Counter Latch Command (See Read Operations)
0 1 Read/Write least significant byte only.
1 0 Read/Write most significant byte only.
1 1 Read/Write least significant byte first, then most
significant byte.
M - Mode
M2 M1 M0
0 0 0 Mode 0
0 0 1 Mode 1
X 1 0 Mode 2
X 1 1 Mode 3
1 0 0 Mode 4
1 0 1 Mode 5
BCD - Binary Coded Decimal
0 Binary Counter 16-bit
1 Binary Coded Decimal (BCD) Counter (4 Decades)
NOTE: Don’t Care bits (X) should be 0 to insure compatibility with
future products.
Possible Programming Sequence
A1 A0
Control Word - Counter 0 1 1
LSB of Count - Counter 0 0 0
MSB of Count - Counter 0 0 0
Control Word - Counter 1 1 1
LSB of Count - Counter 1 0 1
MSB of Count - Counter 1 0 1
Control Word - Counter 2 1 1
LSB of Count - Counter 2 1 0
MSB of Count - Counter 2 1 0
Possible Programming Sequence
A1 A0
Control Word - Counter 0 1 1
Control Word - Counter 1 1 1
Control Word - Counter 2 1 1
LSB of Count - Counter 2 1 0
82C54
4-6
A new initial count may be written to a Counter at any time
without affecting the Counter’s programmed Mode in any way.
Counting will be aff ected as described in the Mode definitions.
The new count m ust follow the programmed count format.
If a Counter is programmed to read/write two-byte counts,
the f ollowing precaution applies . A prog ram m ust not transfer
control between writing the first and second byte to another
routine which also writes into that same Counter. Otherwise,
the Counter will be loaded with an incorrect count.
Read Operations
It is often desirable to read the value of a Counter without
disturbing the count in progress. This is easily done in the
82C54.
There are three possible methods for reading the Counters.
The first is through the Read-Back command, which is
e xplained later. The second is a simple read operation of the
Counter, which is selected with the A1, A0 inputs. The only
requirement is that the CLK input of the selected Counter
must be inhibited by using either the GATE input or external
logic. Otherwise, the count may be in process of changing
when it is read, giving an undefined result.
Counter Latch Command
The other method for reading the Counters involves a spe-
cial software command called the “Counter Latch Com-
mand”. Like a Control Word, this command is written to the
Control Word Register, which is selected when A1, A0 = 11.
Also, like a Control Word, the SC0, SC1 bits select one of
the three Counters, but two other bits, D5 and D4, distin-
guish this command from a Control Word.
.
The selected Counter’s output latch (OL) latches the count
when the Counter Latch Command is received. This count is
held in the latch until it is read by the CPU (or until the Counter
is reprogrammed). The count is then unlatched automatically
and the OL returns to “following” the counting element (CE).
This allows reading the contents of the Counters “on the fly”
without affecting counting in progress. Multiple Counter Latch
Commands may be used to latch more than one Counter.
Each latched Counter’s OL holds its count until read. Counter
Latch Commands do not affect the programmed Mode of the
Counter in any w ay.
If a Counter is latched and then, some time later, latched
again before the count is read, the second Counter Latch
Command is ignored. The count read will be the count at the
time the first Counter Latch Command was issued.
With either method, the count must be read according to the
programmed format; specifically, if the Counter is pro-
grammed for two byte counts, two bytes must be read. The
two bytes do not have to be read one right after the other;
read or write or programming operations of other Counters
may be inserted between them.
Another feature of the 82C54 is that reads and writes of the
same Counter may be interleaved; for example, if the
Counter is programmed for two byte counts, the following
sequence is valid.
LSB of Count - Counter 1 0 1
LSB of Count - Counter 0 0 0
MSB of Count - Counter 0 0 0
MSB of Count - Counter 1 0 1
MSB of Count - Counter 2 1 0
Possible Programming Sequence
A1 A0
Control Word - Counter 2 1 1
Control Word - Counter 1 1 1
Control Word - Counter 0 1 1
LSB of Count - Counter 2 1 0
MSB of Count - Counter 2 1 0
LSB of Count - Counter 1 0 1
MSB of Count - Counter 1 0 1
LSB of Count - Counter 0 0 0
MSB of Count - Counter 0 0 0
Possible Programming Sequence
A1 A0
Control Word - Counter 1 1 1
Control Word - Counter 0 1 1
LSB of Count - Counter 1 0 1
Control Word - Counter 2 1 1
LSB of Count - Counter 0 0 0
MSB of Count - Counter 1 0 1
LSB of Count - Counter 2 1 0
MSB of Count - Counter 0 0 0
MSB of Count - Counter 2 1 0
NOTE: In all four examples, all counters are programmed to
Read/Write two-byte counts. These are only four of many
programming sequences.
Possible Programming Sequence (Continued)
A1 A0
A1, A0 = 11; CS = 0; RD = 1; WR = 0
D7 D6 D5 D4 D3 D2 D1 D0
SC1SC000XXXX
SC1, SC0 - specify counter to be latched
SC1 SC0 COUNTER
00 0
01 1
10 2
1 1 Read-Back Command
D5, D4 - 00 designates Counter Latch Command, X - Don’t Care.
NOTE: Don’t Care bits (X) should be 0 to insure compatibility with
future products.
82C54
4-7
1.Read least significant byte.
2.Write new least significant byte.
3.Read most significant byte.
4.Write new most significant byte.
If a counter is programmed to read or write two-byte counts,
the following precaution applies: A program MUST NOT
transfer control between reading the first and second byte to
another routine which also reads from that same Counter.
Otherwise, an incorrect count will be read.
Read-Back Command
The read-back command allows the user to check the count
value, programmed Mode, and current state of the OUT pin
and Null Count flag of the selected counter(s).
The command is written into the Control Word Register and
has the format shown in Figure 5. The command applies to
the counters selected by setting their corresponding bits D3,
D2, D1 = 1.
The read-back command may be used to latch multiple
counter output latches (OL) by setting the COUNT bit D5 = 0
and selecting the desired counter(s). This signal command
is functionally equivalent to several counter latch commands ,
one for each counter latched. Each counter’s latched count
is held until it is read (or the counter is reprogrammed). That
counter is automatically unlatched when read, but other
counters remain latched until they are read. If multiple count
read-back commands are issued to the same counter with-
out reading the count, all but the first are ignored; i.e., the
count which will be read is the count at the time the first
read-back command was issued.
The read-back command may also be used to latch status
information of selected counter(s) by setting STATUS bit D4
= 0. Status must be latched to be read; status of a counter is
accessed by a read from that counter.
The counter status format is shown in Figure 6. Bits D5
through D0 contain the counter’s programmed Mode exactly
as written in the last Mode Control Word. OUTPUT bit D7
contains the current state of the OUT pin. This allows the
user to monitor the counter’s output via software, possibly
eliminating some hardware from a system.
NULL COUNT bit D6 indicates when the last count written to
the counter register (CR) has been loaded into the counting
element (CE). The exact time this happens depends on the
Mode of the counter and is described in the Mode Definitions,
but until the counter is loaded into the counting element (CE),
it can’t be read from the counter. If the count is latched or read
before this time, the count value will not reflect the new count
just written. The operation of Null Count is shown below.
THIS ACTION: CAUSES:
A. Write to the control word register:(1) . . . . . . . . . . Null Count = 1
B. Write to the count register (CR):(2) . . . . . . . . . . . Null Count = 1
C. New count is loaded into CE (CR - CE). . . . . . . . Null Count = 0
(1) Only the counter specified by the control word will have its null
count set to 1. Null count bits of other counters are unaffected.
(2) If the counter is programmed for two-byte counts (least signifi-
cant byte then most significant byte) null count goes to 1 when
the second byte is written.
If multiple status latch operations of the counter(s) are per-
formed without reading the status, all but the first are ignored;
i.e., the status that will be read is the status of the counter at
the time the first status read-back command w as issued.
FIGURE 7. READ-BACK COMMAND EXAMPLE
A0, A1 = 11; CS = 0; RD = 1; WR = 0
D7 D6 D5 D4 D3 D2 D1 D0
11COUNT STATUS CNT 2 CNT 1 CNT 0 0
D5: 0 = Latch count of selected Counter (s)
D4: 0 = Latch status of selected Counter(s)
D3: 1 = Select Counter 2
D2: 1 = Select Counter 1
D1: 1 = Select Counter 0
D0: Reserved for future expansion; Must be 0
FIGURE 5. READ-BACK COMMAND FORMAT
D7 D6 D5 D4 D3 D2 D1 D0
OUTPUT NULL
COUNT RW1 RW0 M2 M1 M0 BCD
D7: 1 =Out pin is 1
0 =Out pin is 0
D6: 1 =Null count
0 =Count available for reading
D5 - D0 =Counter programmed mode (See Control Word Formats)
FIGURE 6. STATUS BYTE
COMMANDS
DESCRIPTION RESULTD7 D6 D5 D4 D3 D2 D1 D0
11000010Read-Back Count and Status of Counter 0 Count and Status Latched for Counter 0
11100100Read-Back Status of Counter 1 Status Latched for Counter 1
11101100Read-Back Status of Counters 2, 1 Status Latched for Counter 2,
But Not Counter 1
11011000Read-Back Count of Counter 2 Count Latched for Counter 2
11000100Read-Back Count and Status of Counter 1 Count Latched for Counter 1,
But Not Status
11100010Read-Back Status of Counter 1 Command Ignored, Status Already
Latched for Counter 1
82C54
4-8
Both count and status of the selected counter(s) may be
latched simultaneously by setting both COUNT and STATUS
bits D5, D4 = 0. This is functionally the same as issuing two
separate read-back commands at once, and the above dis-
cussions apply here also. Specifically, if multiple count
and/or status read-back commands are issued to the same
counter(s) without any intervening reads, all but the first are
ignored. This is illustrated in Figure 7.
If both count and status of a counter are latched, the first
read operation of that counter will return latched status,
regardless of which was latched first. The next one or two
reads (depending on whether the counter is programmed for
one or two type counts) return latched count. Subsequent
reads return unlatched count.
Mode Definitions
The following are defined for use in describing the operation
of the 82C54.
CLK PULSE:
A rising edge, then a falling edge, in that order, of a
Counter’s CLK input.
TRIGGER:
A rising edge of a Counter’s Gate input.
COUNTER LOADING:
The transfer of a count from the CR to the CE (See “Func-
tional Description”)
Mode 0: Interrupt on Terminal Count
Mode 0 is typically used for event counting. After the Control
Word is written, OUT is initially low, and will remain low until
the Counter reaches zero. OUT then goes high and remains
high until a new count or a new Mode 0 Control Word is writ-
ten to the Counter.
GATE = 1 enables counting; GATE = 0 disables counting.
GATE has no effect on OUT.
After the Control Word and initial count are written to a
Counter, the initial count will be loaded on the next CLK
pulse. This CLK pulse does not decrement the count, so for
an initial count of N, OUT does not go high until N + 1 CLK
pulses after the initial count is written.
If a new count is written to the Counter it will be loaded on
the next CLK pulse and counting will continue from the new
count. If a two-byte count is written, the following happens:
(1)Writing the first byte disables counting. Out is set low
immediately (no clock pulse required).
(2)Writing the second byte allows the new count to be
loaded on the next CLK pulse.
This allows the counting sequence to be synchronized by
software. Again OUT does not go high until N + 1 CLK
pulses after the new count of N is written.
If an initial count is written while GATE = 0, it will still be
loaded on the next CLK pulse. When GATE goes high, OUT
will go high N CLK pulses later; no CLK pulse is needed to
load the counter as this has already been done.
FIGURE 9. MODE 0
NO TES: The follo wing con v entions apply to all mode timing diag rams .
1. Counters are programmed f or binary (not BCD) counting and for
reading/writing least significant byte (LSB) only.
2. The counter is always selected (CS always low).
3. CW stands for “Control Word”; CW = 10 means a control word of
10, Hex is written to the counter.
4. LSB stands for Least significant “byte” of count.
5. Numbers below diagrams are count values. The lower number is
the least significant byte. The upper number is the most signifi-
cant byte. Since the counter is programmed to read/write LSB
only, the most significant byte cannot be read.
6. N stands for an undefined count.
7. Vertical lines show transitions between count values.
CS RD WR A1 A0
01000Write into Counter 0
01001Write into Counter 1
01010Write into Counter 2
01011Write Control Word
00100Read from Counter 0
00101Read from Counter 1
00110Read from Counter 2
00111No-Operation (Three-State)
1XXXXNo-Operation (Three-State)
0 1 1 X X No-Operation (Three-State)
FIGURE 8. READ/WRITE OPERATIONS SUMMARY
CW = 10 LSB = 4
WR
CLK
GATE
OUT
WR
CLK
GATE
OUT
WR
CLK
GATE
OUT
CW = 10 LSB = 3
CW = 10 LSB = 3 LSB = 2
NNNN0
40
30
20
10
0
FF
FF FF
FE
NNNN0
30
20
20
20
10
0FF
FF
NNNN0
30
20
10
20
10
0FF
FF
82C54
4-9
Mode 1: Hardware Retriggerable One-Shot
OUT will be initially high. OUT will go low on the CLK pulse
f ollo wing a trigger to begin the one-shot pulse, and will remain
low until the Counter reaches zero. OUT will then go high and
remain high until the CLK pulse after the ne xt trigger.
After writing the Control Word and initial count, the Counter is
armed. A trigger results in loading the Counter and setting
OUT low on the next CLK pulse, thus starting the one-shot
pulse N CLK cycles in duration. The one-shot is retriggerable,
hence OUT will remain low for N CLK pulses after any trigger.
The one-shot pulse can be repeated without rewriting the
same count into the counter. GATE has no effect on OUT.
If a new count is written to the Counter during a one-shot
pulse, the current one-shot is not affected unless the
Counter is retriggerable. In that case, the Counter is loaded
with the new count and the one-shot pulse continues until
the new count expires.
FIGURE 10. MODE 1
Mode 2: Rate Generator
This Mode functions like a divide-by-N counter. It is typically
used to generate a Real Time Clock Interrupt. OUT will ini-
tially be high. When the initial count has decremented to 1,
OUT goes low for one CLK pulse. OUT then goes high
again, the Counter reloads the initial count and the process
is repeated. Mode 2 is periodic; the same sequence is
repeated indefinitely. For an initial count of N, the sequence
repeats every N CLK cycles.
GATE = 1 enables counting; GATE = 0 disables counting. If
GATE goes low during an output pulse, OUT is set high
immediately. A trigger reloads the Counter with the initial
count on the next CLK pulse; OUT goes low N CLK pulses
after the trigger. Thus the GATE input can be used to syn-
chronize the Counter.
After writing a Control Word and initial count, the Counter will
be loaded on the next CLK pulse. OUT goes low N CLK
pulses after the initial count is written. This allows the
Counter to be synchronized by software also.
Writing a new count while counting does not affect the current
counting sequence. If a trigger is received after writing a new
count but before the end of the current per iod, the Counter will
be loaded with the new count on the ne xt CLK pulse and count-
ing will continue from the end of the current counting cycle.
FIGURE 11. MODE 2
WR
CLK
GATE
OUT
WR
CLK
GATE
OUT
WR
CLK
GATE
OUT
NNNN 0
30
20
10
0FF
FF 0
30
2
N
CW = 12 LSB = 3
CW = 12 LSB = 3
CW = 12 LSB = 2 LSB = 4
NNNN 0
20
10
0
FF
FF FF
FE 0
40
3
N
NNNN 0
30
20
10
30
20
10
0
N
NNNN 0
20
10
30
20
10
3
0
3
NNNN 0
20
20
30
20
10
3
0
3
NNNN 0
30
20
10
50
40
3
0
4
WR
CLK
GATE
OUT
CW = 14 LSB = 3
WR
CLK
GATE
OUT
CW = 14 LSB = 3
WR
CLK
GATE
OUT
CW = 14 LSB = 4 LSB = 5
82C54
4-10
Mode 3: Square Wave Mode
Mode 3 is typically used for Baud rate generation. Mode 3 is
similar to Mode 2 except for the duty cycle of OUT. OUT will
initially be high. When half the initial count has expired, OUT
goes low for the remainder of the count. Mode 3 is per iodic;
the sequence above is repeated indefinitely. An initial count
of N results in a square wave with a period of N CLK cycles.
GATE = 1 enables counting; GATE = 0 disables counting. If
GATE goes low while OUT is low, OUT is set high immedi-
ately; no CLK pulse is required. A trigger reloads the
Counter with the initial count on the next CLK pulse. Thus
the GATE input can be used to synchronize the Counter.
After writing a Control Word and initial count, the Counter will
be loaded on the next CLK pulse. This allows the Counter to
be synchronized by software also.
Writing a new count while counting does not affect the cur-
rent counting sequence. If a trigger is received after writing a
new count but before the end of the current half-cycle of the
square wave, the Counter will be loaded with the new count
on the next CLK pulse and counting will continue from the
new count. Otherwise, the new count will be loaded at the
end of the current half-cycle.
FIGURE 12. MODE 3
Mode 3 is Implemented as Follows:
EVEN COUNTS: OUT is initially high. The initial count is
loaded on one CLK pulse and then is decremented by two
on succeeding CLK pulses. When the count expires, OUT
changes value and the Counter is reloaded with the initial
count. The above process is repeated indefinitely.
ODD COUNTS: OUT is initially high. The initial count is loaded
on one CLK pulse, decremented b y one on the ne xt CLK pulse,
and then decremented by two on succeeding CLK pulses.
When the count expires, OUT goes low and the Counter is
reloaded with the initial count. The count is decremented by
three on the next CLK pulse, and then by two on succeeding
CLK pulses. When the count e xpires, OUT goes high again and
the Counter is reloaded with the initial count. The above pro-
cess is repeated indefinitely. So for odd counts, OUT will be
high f or (N + 1)/2 counts and low for (N - 1)/2 counts.
Mode 4: Software Triggered Mode
OUT will be initially high. When the initial count expires , OUT
will go low for one CLK pulse then go high again. The count-
ing sequence is “Triggered” by writing the initial count.
GATE = 1 enables counting; GATE = 0 disables counting.
GATE has no effect on OUT.
After writing a Control Word and initial count, the Counter will be
loaded on the next CLK pulse. This CLK pulse does not decre-
ment the count, so f or an initial count of N, OUT does not strobe
low until N + 1 CLK pulses after the initial count is written.
If a new count is written during counting, it will be loaded on
the next CLK pulse and counting will continue from the new
count. If a two-byte count is written, the following happens:
(1)Writing the first byte has no effect on counting.
(2)Writing the second byte allows the new count to be
loaded on the next CLK pulse.
This allows the sequence to be “retriggered” by software. OUT
strobes low N + 1 CLK pulses after the ne w count of N is written.
NNNN 0
20
40
20
40
20
40
2
0
40
40
2
NNNN 0
40
20
50
20
50
40
2
0
50
50
2
NNNN 0
20
40
20
20
20
40
2
0
40
40
2
WR
CLK
GATE
OUT
CW = 16 LSB = 4
WR
CLK
GATE
OUT
WR
CLK
GATE
OUT
CW = 16 LSB = 5
CW = 16 LSB = 4
82C54
4-11
FIGURE 13. MODE 4
Mode 5: Hardware Triggered Strobe (Retriggerable)
OUT will initially be high. Counting is triggered by a rising
edge of GATE. When the initial count has expired, OUT will
go low for one CLK pulse and then go high again.
After writing the Control Word and initial count, the counter
will not be loaded until the CLK pulse after a trigger. This
CLK pulse does not decrement the count, so for an initial
count of N, OUT does not strobe low until N + 1 CLK pulses
after trigger.
A trigger results in the Counter being loaded with the initial
count on the next CLK pulse. The counting sequence is trig-
gerable. OUT will not strobe low for N + 1 CLK pulses after
any trigger GATE has no effect on OUT.
If a new count is written during counting, the current count-
ing sequence will not be affected. If a trigger occurs after the
new count is written but before the current count expires, the
Counter will be loaded with new count on the next CLK pulse
and counting will continue from there.
FIGURE 14. MODE 5
Operation Common to All Modes
Programming
When a Control Word is written to a Counter, all Control
Logic, is immediately reset and OUT goes to a known initial
state; no CLK pulses are required for this.
Gate
The GATE input is always sampled on the rising edge of
CLK. In Modes 0, 2, 3 and 4 the GATE input is level sensi-
tive, and logic level is sampled on the rising edge of CLK. In
modes 1, 2, 3 and 5 the GATE input is rising-edge sensitive.
In these Modes, a rising edge of Gate (trigger) sets an edge-
sensitive flip-flop in the Counter. This flip-flop is then sam-
pled on the next rising edge of CLK. The flip-flop is reset
immediately after it is sampled. In this way, a trigger will be
detected no matter when it occurs - a high logic level does
not have to be maintained until the next rising edge of CLK.
Note that in Modes 2 and 3, the GATE input is both edge-
and level-sensitive.
NNNN 0
20
10
0
FF
FF FF
FE FF
FD
0
3
WR
CLK
GATE
OUT
CW = 18 LSB = 3
WR
CLK
GATE
OUT
WR
CLK
GATE
OUT
CW = 18 LSB = 3
CW = 18 LSB = 3
NNN 0
30
20
10
20
10
0FF
FF
NNNN 0
30
30
20
10
0FF
FF
0
3
LSB = 2
N
NNNN 0
30
20
10
0FF
FF 0
3
WR
CLK
GATE
OUT
CW = 1A LSB = 3
NNNN 0
30
20
30
20
1
NNNN 0
30
20
10
0
FF
FF FF
FE
WR
CLK
GATE
OUT
CW = 1A LSB = 3
WR
CLK
GATE
OUT
CW = 1A LSB = 3
N
NN 0
0
FF
FF
LSB = 5
N0
50
4
82C54
4-12
Counter
New counts are loaded and Counters are decremented on
the falling edge of CLK.
The largest possible initial count is 0; this is equiv alent to 216
for binary counting and 104 for BCD counting.
The counter does not stop when it reaches zero. In Modes 0,
1, 4, and 5 the Counter “wraps around” to the highest count,
either FFFF hex for binar y counting or 9999 for BCD count-
ing, and continues counting. Modes 2 and 3 are periodic; the
Counter reloads itself with the initial count and continues
counting from there.
FIGURE 15. GATE PIN OPERATIONS SUMMARY
FIGURE 16. MINIMUM AND MAXIMUM INITIAL COUNTS
SIGNAL
STATUS
MODES LOW OR
GOING LOW RISING HIGH
0 Disables Counting - Enables Counting
1 - 1) Initiates
Counting
2) Resets output
after next clock
-
2 1) Disables
counting
2) Sets output im-
mediately high
Initiates Counting Enables Counting
3 1) Disables
counting
2) Sets output im-
mediately high
Initiates Counting Enables Counting
4 1) Disables
Counting - Enables Counting
5 - Initiates Counting -
MODE MIN COUNT MAX COUNT
010
110
220
320
410
510
NOTE: 0 is equivalent to 216 for binary counting and 104 for BCD
counting.
82C54
4-13
)
Absolute Maximum Ratings Thermal Information
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+8.0V
Input, Output or I/O Voltage . . . . . . . . . . . . GND-0.5V to VCC +0.5V
ESD Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Class 1
Operating Conditions
Operating Voltage Range . . . . . . . . . . . . . . . . . . . . . +4.5V to +5.5V
Operating Temperature Range
C82C54, C82C54-10, -12. . . . . . . . . . . . . . . . . . . . 0oC to +70oC
I82C54, I82C54-10, -12 . . . . . . . . . . . . . . . . . . . . -40oC to +85oC
M82C54, M82C54-10, -12 . . . . . . . . . . . . . . . . . -55oC to +125oC
Thermal Resistance (Typical) θJA (oC/W) θJC (oC/W)
CERDIP Package . . . . . . . . . . . . . . . . 55 12
CLCC Package . . . . . . . . . . . . . . . . . . 65 14
PDIP Package . . . . . . . . . . . . . . . . . . . 60 N/A
PLCC Package . . . . . . . . . . . . . . . . . . 65 N/A
SOIC Package. . . . . . . . . . . . . . . . . . . 75 N/A
Storage Temperature Range. . . . . . . . . . . . . . . . . .-65oC to +150oC
Maximum Junction Temperature Ceramic Package . . . . . . .+175oC
Maximum Junction Temperature Plastic Package. . . . . . . . .+150oC
Maximum Lead Temperature Package (Soldering 10s) . . . . +300oC
(PLCC and SOIC - Lean Tips Only)
Die Characteristics
Gate Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2250 Gates
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation
of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
DC Electrical Specifications VCC = +5.0V ± 10%, TA = 0oC to +70oC (C82C54, C82C54-10, C82C54-12)
TA = -40oC to +85oC (I82C54, I82C54-10, I82C54-12)
TA = -55oC to +125oC (M82C54, M82C54-10, M82C54-12
SYMBOL PARAMETER MIN MAX UNITS TEST CONDITIONS
VIH Logical One Input Voltage 2.0 - V C82C54, I82C54
2.2 - V M82C54
VIL Logical Zero Input Voltage - 0.8 V
VOH Output HIGH Voltage 3.0 - V IOH = -2.5mA
VCC -0.4 - V IOH = -100µA
VOL Output LOW Voltage - 0.4 V IOL = +2.5mA
II Input Leakage Current -1 +1 µA VIN = GND or VCC
DIP Pins 9,11,14-16,18-23
IO Output Leakage Current -10 +10 µA VOUT = GND or VCC
DIP Pins 1-8
ICCSB Standby Power Supply Current - 10 µAV
CC = 5.5V, VIN = GND or VCC,
Outputs Open, Counters
Programmed
ICCOP Operating Power Supply Current - 10 mA VCC = 5.5V,
CLK0 = CLK1 = CLK2 = 8MHz,
VIN = GND or VCC,
Outputs Open
Capacitance TA = +25oC; All Measurements Referenced to Device GND, Note 1
SYMBOL PARAMETER TYP UNITS TEST CONDITIONS
CIN Input Capacitance 20 pF FREQ = 1MHz
COUT Output Capacitance 20 pF FREQ = 1MHz
CI/O I/O Capacitance 20 pF FREQ = 1MHz
NOTE:
1. Not tested, but characterized at initial design and at major process/design changes.
82C54
4-14
AC Electrical Specifications VCC = +5.0V ± 10%, TA = 0oC to +70oC (C82C54, C82C54-10, C82C54-12)
TA = -40oC to +85oC (I82C54, I82C54-10, I82C54-12)
TA = -55oC to +125oC (M82C54, M82C54-10, M82C54-12)
SYMBOL PARAMETER
82C54 82C54-10 82C54-12
UNITS TEST
CONDITIONSMIN MAX MIN MAX MIN MAX
READ CYCLE
(1) TAR Address Stable Before RD 30 - 25 - 25 - ns 1
(2) TSR CS Stable Before RD 0-0-0-ns 1
(3) TRA Address Hold Time After RD0-0-0-ns 1
(4) TRR RD Pulse Width 150 - 95 - 95 - ns 1
(5) TRD Data Delay from RD - 120 - 85 - 85 ns 1
(6) TAD Data Delay from Address - 210 - 185 - 185 ns 1
(7) TDF RD to Data Floating 5 85 5 65 5 65 ns 2, Note 1
(8) TRV Command Recovery Time 200 - 165 - 165 - ns
WRITE CYCLE
(9) TAW Address Stable Before WR 0-0-0-ns
(10) TSW CS Stable Before WR 0-0-0-ns
(11) TWA Address Hold Time After WR0-0-0-ns
(12) TWW WR Pulse Width 95 - 95 - 95 - ns
(13) TDW Data Setup Time Before WR 140 - 95 - 95 - ns
(14) TWD Data Hold Time After WR 25 - 0 - 0 - ns
(15) TRV Command Recovery Time 200 - 165 - 165 - ns
CLOCK AND GATE
(16) TCLK Clock Period 125 DC 100 DC 80 DC ns 1
(17) TPWH High Pulse Width 60 - 30 - 30 - ns 1
(18) TPWL Low Pulse Width 60 - 40 - 30 - ns 1
(19) TR Clock Rise Time - 25 - 25 - 25 ns
(20) TF Clock Fall Time - 25 - 25 - 25 ns
(21) TGW Gate Width High 50 - 50 - 50 - ns 1
(22) TGL Gate Width Low 50 - 50 - 50 - ns 1
(23) TGS Gate Setup Time to CLK 50 - 40 - 40 - ns 1
(24) TGH Gate Hold Time After CLK 50 - 50 - 50 - ns 1
(25) TOD Output Delay from CLK - 150 - 100 - 100 ns 1
(26) TODG Output Delay from Gate - 120 - 100 - 100 ns 1
(27) TWO OUT Delay from Mode Write - 260 - 240 - 240 ns 1
(28) TWC CLK Delay for Loading 0 55 0 55 0 55 ns 1
(29) TWG Gate Delay for Sampling -5 40 -5 40 -5 40 ns 1
(30) TCL CLK Setup for Count Latch -40 40 -40 40 -40 40 ns 1
NOTE:
1. Not tested, but characterized at initial design and at major process/design changes.
82C54
4-15
Timing Waveforms
FIGURE 17. WRITE
FIGURE 18. READ
FIGURE 19. RECOVERY
FIGURE 20. CLOCK AND GATE
A0 - A1
CS
DATA BUS
WR
(12)
tWW
(13)
tDW
(10)
tSW
(9)
tAW
VALID
tWD (14)
tWA (11)
VALID
A0 - A1
CS
RD
DATA BUS
(2)
tSR
(6)
tAD
(5)
tRD
(4)
tRR
(7)
tDF
tRA (3)
tAR (1)
(8) (15)
tRV
RD, WR
WR
CLK
GATE
OUT
MODE COUNT
(SEE NOTE)
(17)
tPWH (18)
tPWL
(16)
tCLK tGS
(21)
tGW
(27)
tWO
tGS
(23)
tGH
(24)
tGL
tODG (26)
tF (20)
tOD (25)
tGH (24)
NOTE: LAST BYTE OF COUNT BEING WRITTEN
(19)
tR
(22)
(23)
tCL (30)
tWC (28)
82C54
4-16
Burn-In Circuits
MD 82C54 CERDIP
MR 82C54 CLCC
NOTES:
1. VCC = 5.5V ±0.5V
2. GND = 0V
3. VIH = 4.5V ±10%
4. VIL = -0.2V to 0.4V
5. R1 = 47kΩ±5%
6. R2 = 1.0kΩ±5%
7. R3 = 2.7kΩ±5%
8. R4 = 1.8kΩ±5%
9. R5 = 1.2kΩ±5%
10. C1 = 0.01µF Min
11. F0 = 100kHz ±10%
12. F1 = F0/2, F2 = F1/2, ...F12 = F11/2
R1
R1
R1
R1
R1
R1
R1
R1
R2
R1
R1
R1
R1
R1
R2
R1
R1
R2
R1
VCC
GND
Q5
Q4
A
F1
Q7
A
Q3
F2
Q8
Q2
VCC
GND
F9
F11
F0
A
Q6
GND
Q1
F10
F12
VCC
A
1
2
3
4
5
6
7
8
9
10
11
12
16
17
18
19
20
21
22
23
24
15
14
13
VCC C1
R4
R3
23
24
25
22
21
20
19
11
3 2 14
14 15 16 17 1812 13
28 27 26
10
5
6
7
8
9
VCC/2 Q6 GNDOPEN
VCC/2 F1Q7
R1
R1
R1
R1
R2
R5
GND
Q5
Q4
Q8
OPEN
F2
VCC/2
R1
R1
R1
R1
R1
R2
F9
F10
F11
OPEN
GND
F12
F0
R5 R1 R5 R1 R2
R1R1R1R1R1
VCC Q2 Q1 OPEN
C1
Q3 VCC
VCC
82C54
4-17
Die Characteristics
DIE DIMENSIONS:
129mils x 155mils x 19mils
(3270µm x 3940µm x 483µm)
METALLIZATION:
Type: Si-Al-Cu
Thickness: Metal 1: 8kű 0.75kÅ
Metal 2: 12kű 1.0kÅ
GLASSIVATION:
Type: Nitrox
Thickness: 10kű 3.0kÅ
Metallization Mask Layout
82C54
CS
A1
A0
CLK2
OUT2
GATE2
D4
D3
D2
D1
D0
CLK0
D5 D6 D7 VCC WR RD
OUT0 GATE0 GND OUT1 GATE1 CLK1
82C54
